Counterbalance crank



April 18, 1939. w. c. TROUT 2,155,174

, COUNTERBALANCE CRANK Original Filed July 12, 1934 29 E 0 mum I5 22 k 1(Z g (28 K 21 5 gwuc/wkw WALTER G. TROUT Y $31M Patented Apr. 18, 1939 UNITED STATES PATENT OFFICE COUNTERBALANCE CRANK Walter C. Trout, Lufkin, Tex., assignor to Lufkin Foundry & Machine Company, Luikin, Tex., a

corporation '7 Claims.

The invention relates to an improvement in counterbalanced cranks for oil well pumping units.

This application is a division of my application Serial No. 734:,753, filed July 12, 1934.

In the pumping of oil wells it is desirable to counterbalance the load on the reciprocating walking beam so that a minimum of power will be necessary and a smoothness of operation obtained. At the same time it is also desirable to release the counter-balanced weight from the crank arm or pumping mechanism so that the pumping unit may be used for removing the pump or tubing from the well, or in otherwise performing what is known as servicing operations.

One of the objects of the invention is to provide a combination crank and counter-ba1ance arm wherein the counter-balance may be adjusted longitudinally of the crank arm and increased in size as desired in order to obtain the necessary counter-balancing action.

Another object of the invention is to provide a combination crank and counter-balanced weight made up as a single unit which may be adjusted as to length.

Another object of the invention is to provide a counter-balanced crank which is made up of a plurality of independent sections adapted to be clamped together to form the crank and counterbalance.

A still further object of the invention is to provide a counter-balance weight attachment for crank arms such that the weight portion may be readily detached from the crank portion.

It is also an object of the invention to provide a counter-balanced weight attachment to the crank arm such that the counter-balance may be removed by being detached laterally from the crank arm;

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawing wherein:

Fig. 1 is a diagrammatic view of a pumping unit installation in combination with the walking beam and pitman rod.

Fig. 2 is a side View of one form of counterbalanced crank unit wherein the weight may be varied and the length of the crank adjusted by adding or inserting independent segments.

Fig. 3 is an edge view of the crank and weight of Fig. 1.

In Fig. 1 the Sampson post is indicated at 2 and has mounted thereon the usual form of walking beam 3, which is pivoted by means of the center iron 4. The right-hand end of this walking beam 3 is connected with the string of rods and the pump in the well so that the rocking movement of the walking beam serves to perform the pumping action in the well. a

The rocking movement of the walking beam 3 is accomplished by means of the pitman rod 5 which is connected to a crank 5 which is in turn caused to rotate by a shaft 7 extending from the pumping unit indicated generally at 8.

A preferred form of the crank and weight construction is illustrated herewith. As best seen-in Fig. 2 the crank is made upof a plurality of parts including the hub It! which has the opening ll therein by which the hub is keyed to the shaft lb 1. It will be particularly noted that the hub 10 is but slightly larger than required to carry the opening Ii and that adjacent this body H) are a plurality of plates 12 and I3. These plates, as well as the body it), are perforated to receive the attaching bolts l5. The weight structure is indicated generally at 16 and has an outwardly extending portion which is provided with a crank pin opening I! therein. The bolts l5 pass through the openings 18 in the weight structure and are arranged to fit quite closely within the bushing I!) in each of the openings l8. In this manner there will be no lost motion between the weight and the bolt members so that when the nuts 2! and 22 are drawn up tightly on each 3 end of the bolts the body I0, plates I2 and I3, and the weight 16 will be firmly clamped together as a unitary structure.

It is often desirable to change the length of the stroke of the pump and different weights are arranged to operate with a different stroke. With this in mind, the plates l2 and 13 have been provided so that a suitable number of plates may be inserted in order to get the length of stroke desired, it being understood that the length of stroke is the distance between the center of the shaft in the opening I! and the center of the wrist pin in the opening ll. Thus by adding or removing the desired number of plates l2 the distance may be varied and the nuts 2! and 22 set up to firmly clamp the parts together. With devices heretofore in use a number of crank pin or wrist pin openings have been provided, any one of which might be selected for use.

It will be noted that the plates and the weight [6 are arranged with cooperating tongue and groove portions 25 so that there can be no creeping movement between the parts when they are firmly clamped in position. Each well being counter-balanced has peculiarities of its own and the counter-balancing must be adjusted for .that particular well. With this in mind, a plurality of weights 28 have been provided which can be clamped by means of the bolts 29 upon the shoulders 30 of the weight I6.

It will be apparent from the foregoing description that the weight [8 is always closely adjacent the connection of the wrist pin in the opening I! because of the fact that the wrist pin opening is formed in the weight structure itself. The weight may be adjusted longitudinally with respect to the shaft to vary the counter-balancing features and the amount of counter-balance may be varied by varying the number of the plates 28 which are provided. With these adjustments it is possible to obtain almost any desired variation in counterbalancing which is necessary.

While a specific form of the invention has been shown, it is to be understood that the invention is not confined thereto, but that changes may be made in the construction and combination of parts without departing from the spirit of the inven tion.

What is claimed is:

1. In a counterbalance device for well pumping units, a hub portion to receive a crank shaft, a crank arm portion including a counterbalance weight thereon, means in the crank arm portion to connect a pitman rod thereto, and connecting members adjustably connecting said hub portion and said crank arm to adjust the radial position of said crank arm to vary the length of the stroke.

2. A pumping unit counterbalanced crank arm comprising a hub portion to receive the crank shaft, a counterweight, a wrist pin opening in said weight, a plurality of plates spaced between said hub and weight, and means to clamp said hub, weight and plates together to make up the crank arm.

3. An adjustable length crank arm for pumping units including a body portion, a pin receiving portion, and plate members adapted to be inserted between said body and pin portion to vary the length of the crank stroke, and means to clamp the parts together to make a unitary crank arm.

4. A crank arm made up of parts comprising a hub, spacer plates, and a T-shaped weight member, a pair of through bolts passing through said parts and nuts thereon to clamp the parts together, a crank shaft opening in said hub, and a Wrist pin opening in said weight.

5. A combination crank arm and counterbalance weight assembly comprising a body weight, a single opening therein to receive a wrist pin, lateral extensions on said body weight, means to clamp additional weights on each extension, a hub portion, a crankshaft opening therein, and means to which both said hub and body may be clamped and means for clamping the body weight and the hub portion to said last mentioned means to hold said assembly together to serve as a counterbalanced crank arm when the load is connected to said wrist pin opening.

6. A combination crank arm and counterbalance weight assembly comprising a body Weight, a single opening therein to receive a wrist pin, lateral extensions on said body weight, means to clamp additional weights on each extension, a hub portion, a crankshaft opening therein, and means to which both said hub and body may be clamped and means for clamping the body weight and the hub portion to said last mentioned means to hold said assembly together to serve as a counterbalanced crank arm When the load is connected to said wrist pin opening, said first mentioned means being adjustable as to length to position said wrist pin opening in diiferent radial positions.

I. In a pumping unit counterbalance crank arm, the combination of a portion to receive a crank shaft, a counterweight adapted to be attached to said portion and having a wrist pin opening therein, and means for connecting the counterweight to the portion at predetermined distances from the center of rotation so that the stroke length and counterbalancing effect may be varied.

WALTER C. TROUT. 

